Structural Volume Changes in Photoinduced Electron Transfer Reactions. Laser-Induced Optoacoustic Studies of Speciation during the Quenching Reaction of Excited Ru(bpy)₃²⁺ by Fe(III) in Aqueous Solutions

Abstract

Laser-induced optoacoustic spectroscopy has been applied to the photoinduced electron-transfer reaction between Ru(bpy)3 2+ and various salts of Fe(III) [Fe(ClO4)3, Fe2(SO4)3, and FeCl3]. The reaction volume changes associated with photoinduced ligand exchange derived from these measurements allowed the determination of partial molar volumes at high dilutions of several species such as FeSO4, FeSO4 +, Fe(SO4)2 -, Fe(OH)2+, FeCl+, FeCl2+, and FeCl2 +, not attainable from other techniques. The volume change of oxidation of Ru(bpy)3 2+ to Ru(bpy)3 3+ at high dilution was also calculated.

Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

“…For instance, the structural volume changes observed for the quenching reaction of excited Ru(bpy) 3 2ϩ by various salts of Fe() in aqueous solutions strongly depended on the nature of the counterion of the iron salts, due to speciation effects. 100 By using the PAS results together with the formation constants of the several iron complexes present before and after the reaction, the partial molar volumes at high dilution of various species were determined.…”

Photoinduced Structural Volume Changes in Aqueous Solutions of Blepharismin

“…involving production of ions or an increase in the dipole moment, should result in a contraction due to electrostrictive forces (50) and, in the case of a reversible charge separation, an expansion should follow, related to charge recombination (40, 5 1). However the complex nature of solute-solvent specific interactions (52) often renders the electrostrictive theory not adequate to describe the observed volume changes and charge separation has been also found to yield expansions in several cases (53)(54)(55).…”

Thermodynamic changes associated with the formation of the hydrated electron after photoionization of inorganic anions: a time-resolved photoacoustic study

“…This technique has been widely employed to investigate enthalpy and volume changes of photoinduced reactions in solution. 9 In previous reports, we demonstrated the suitability of TRP to obtain volume changes and partial molar volumes of the hydrated proton, 10 of ionic species produced by speciation changes in photoinduced electron-transfer reactions, 11 and of ion radicals generated in photodissociation reactions. 12 The partial molar volumes are relevant parameters in elucidating structural interactions (i.e.…”